Wireless Smart Grid systems could suffer severely from radio-frequency interference (RFI) caused by sparking noise sources associated with the electrical infrastructure. These sources are commonly not associated directly with the power conductors; rather, the air in small gaps between mounting hardware or other conductors in close proximity to the power conductors themselves (and therefore in their intense electrical field) breaks down at or near a maximum of the AC waveform and produces groups of short, high energy, high frequency impulses that have spectral components past 800 MHz (Mary Loftness, AC Power Interference Handbook, 3rd ed., ISBN 978-0-9653760-3-7, Ch. 1). These impulses can cause severe interference to nearby radio and television receivers (the system essentially forms a spark transmitter using the power lines as an antenna), and therefore could be a significant problem for wireless smart grid networks. In addition, the presence of this interference is indicative of loose, weathered, or defective electrical hardware, which could represent a safety hazard to utility employees and the public and/or the potential for a service outage.
A principal difficulty with AC power-related RFI is that the impulses produce very wideband noise; their spectra frequently extend past 1 GHz. Since the lower-frequency spectral components have more energy in them, they frequently cause interference over a wider area than do the higher-frequency components; this can make the location of the source very difficult if one uses the lower frequencies exclusively in the search, especially when one considers the complex standing-wave pattern that can exist on the power lines.
The state-of-the-art method for locating AC power interference sources (Marvin O. Loftness, “RFI Source-locating on Power Lines—an Update,” IEEE Transactions on Power Delivery, Vol. 4, No. 2, April 1989, pp. 1137-1144) is for the investigator to move up in frequency as he approaches the source, for better location discrimination. Starting at the frequency generating the complaint (usually HF or VHF), he moves up to UHF and finally 800 or 900 MHz (V. L. Chartier, R. Sheridan, J. N. DiPlacido, and M. O. Loftness, “Electromagnetic Interference Measurements at 900 MHz on 230-kV and 500-kV Transmission Lines,” IEEE Transactions on Power Delivery, Vol. 1, No. 2, April 1986, pp. 140-149) for the final identification of the specific power pole containing the defect. Interestingly, these final frequencies (˜900 MHz) used for pole-specific identification are also those expected to be used most often by wireless smart grid systems.
Existing known art related to the detection and correction of such conditions (e.g., U.S. Pat. No. 7,368,918 to Henson, et al.), rely on dedicated sensors to detect the interference.